1) Field of the Invention
The invention relates to a rotary tool, in particular a drill, comprising a cutting head which extends along a rotation axis and has a plurality of main cutting edges which extend radially outward and each end at the circumference of the cutting head at a cutting corner having a corner bevel.
2) Description of the Related Art
Such a cutting tool designed as a rotary tool can be seen, for example, from DE 202 09 767 U1.
During the cutting operation, for example using drills, but also by means of reamers, milling cutters, in particular end mills, step drills, deep-hole drills or “three-lipped cutters”, there is generally the problem that the cutting corner is subjected to both high mechanical and high thermal loading in these rotary tools. In order to reduce this loading, it is known to provide “corner bevels” at the cutting corner. Due to this corner bevel, the main cutting edge does not run out rectilinearly to the circumference. No cutting corner having a sharp point is therefore formed at the transition between the main cutting edge and the outer circumference. Due to this measure, the cutting corner is therefore subjected to less loading overall and therefore the service life of the cutting tool can be increased. At the same time, however, there is the problem that, when through-openings, for example through-bores, are being formed, an undesirable burr at the exit of the drill hole is increased. This often requires subsequent treatment of the burr in order to achieve the drilling quality required.
In order to counter “fraying of the drill hole”, provision is made in the twist drill which can be seen from DE 202 09 7676 U1 for a re-working secondary cutting edge to adjoin a respective main cutting edge. A flank adjoining the main cutting edge therefore extends right up to the respective re-working secondary cutting edge assigned to the respective main cutting edge. In this case, the secondary cutting edge is arranged to be set back axially from the main cutting edge.
The object of the invention is to specify a rotary cutting tool which ensures a long service life and at the same time allows through-openings having as small a burr as possible to be formed.